“Don’t say that you’re robbing Peter to pay Paul, when Peter’s living in a 10-room house with four kids, and he’s busted through all his credit cards — because that’s what BPS has done until now,” he said at a public forum hosted by the Boston Foundation that reviewed the first 100 days of school under Superintendent Tommy’s Chang’s tenure.

In the six years he headed the education committee, Connolly said, the city never reduced School Department funding to reflect students lost to charter schools, and the district did not curtail its spending to reflect decreased enrollment. Connolly said the district now has as many as 20,000 to 30,000 empty seats across more than 120 school buildings.

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District leaders, he said, have “spread those students out across those 120 buildings to make it seem like the problem isn’t as severe as it is, and then in the process have understaffed schools with half-filled classrooms and tens of millions of dollars that just evaporate every year.”

Connolly said many obstacles to serving Boston’s students are tied to budget issues long predating Chang’s tenure as superintendent and Mayor Martin J. Walsh’s taking office. Walsh defeated Connolly 52 percent to 48 percent in the mayoral race.

At the forum, educators and advocates called for more attention to the social, emotional, and mental health needs of students, many of whom have experienced trauma and need support to focus on learning, they said.

They also called on Boston Public Schools to work to close persistent racial gaps in educational opportunities and achievement. Chang proposes to create greater educational opportunities in part by expanding access in the upper elementary grades to rigorous coursework of the type used in advanced-work classes.

Rather than limiting such work to students who score well on a standardized test — a group that is disproportionately white or Asian — the superintendent plans a pilot program that would set demanding work for all fourth-grade students in participating schools.

Under the current system, white children, who make up only 13 percent of the district’s students, constitute 27 percent of advanced-work students, Chang said at Wednesday’s forum. Conversely, Hispanic and Latino children, who make up 39 percent of the district, and black children, who constitute 37 percent, each account for only 22 percent of advanced-work students.